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Emergence

Posted by timothy on Wed Dec 15, 2004 04:50 PM
from the arise-ye-ants dept.
Tangurena writes "Emergence is a field that is trying to come to grips with how new behavior emerges out of smaller units. There is no gene that determines the behavior of a hive of bees or colony of ants, but the behavior of the nest emerges from the individuals within. Some people are using cellular automata as a means of explaining higher order behavior (like Wolfram in A New Kind of Science )." Read on for Tangurena's review of Steven Johnson's 2002 book Emergence: the Connected lives of Ants, Brains, Cities and Software.

The author makes a point that there are 3 main camps of scientific study.

  1. The study of simple systems - under a few dozen variables, like electromagnetism, or celestial mechanics.
  2. The study of stochastic systems - few million to few billion variables, like actuarial sciences and genetics.
  3. The study of disorganized complexity. Systems in the middle between a dozen and a few million variables, where the second order characteristics - how they interact, is of primary concern.

Deduction and induction work for the first two camps, but for the third, the interactions cause actions and reactions which are what scientists politely call counter intuitive, meaning your first thought is Huh? Or, in other words, it behaves quite differently from what your instincts and (so-called) common sense would tell you.

There are five basic principles for developing a system (or simulation of one) which can express emergent behavior:

  1. More is different. You get a very different behavior of the system when certain thresholds are reached.
  2. Ignorance is useful. Ants communicate with a vocabulary of around 20 words/ideas.
  3. Encourage random encounters. Much of the behavior of an ant colony comes from them just bumping into each other (or external things like food, or my foot).
  4. Look for patterns in the signs. Even with the limited vocabulary of ants, they can also express things based on the decay in the pheromones they deposit.
  5. Pay attention to your neighbors. Also described as "local information can lead to global wisdom."

One of the enduring myths we have, is that of the Ant Queen. The myth supposes that there is some central planning done in an ant colony. Instead, the queen exists only to pop eggs out. Male ants have such short lives, that in most species of ants, they have no mouths to eat with; they just don't live long enough to get hungry. The production of warriors and workers is stimulated by pheromones in the colony. Information on where to gather food is gathered through random acts of bumping into things. There is no ant which tells another to go lift that bale or tote that barge. It appears that our intelligence is a by-product of the neural interactions of our brains.

The economist Jane Jacobs had been studying things like this for years, and has been demonized by the majority of economists: they want to believe in some centralized controlling force, control that force, and you control the development of your economic system. People reading her books tend to think she worships sidewalks, instead, she values the communication that can only happen on sidewalks; people meeting each other and exchanging words. You can't say "hi" to your neighbors if you are each zipping past each other on the freeway.

One can experiment with emergent behavior with some software tools. The author explains a few, of which you are most likely to have experience with SimCity.

The main difference between chaos theory and emergent behavior theory lies in a couple important differences. A chaotic system has a number of determinable feedback loops, all of which are (usually critically) dependent upon the starting conditions. Emergent behavior has more to do with feedback loops causing totally different behavior, and when some threshold (usually population) is passed, the nature of the system drastically changes.

If you are looking for sample code to simulate things, you won't find it in this book. If, however, you want to get an overview of where this field is coming from, read this book.


You can purchase Emergence: the Connected lives of Ants, Brains, Cities and Software from bn.com. Slashdot welcomes readers' book reviews -- to see your own review here, carefully read the book review guidelines, then visit the submission page.

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  • by Neil Blender (555885) <neilblender@gmail.com> on Wednesday December 15 2004, @04:54PM (#11097352)
    Groupthink
  • by utexaspunk (527541) on Wednesday December 15 2004, @04:57PM (#11097404)
    While A New Kind of Science may have lots of pretty pictures, and may be a decent survey of the field of cellular automata and its potential applications, and while Stephen Wolfram is no doubt a smart man, the quality of the book is overshadowed by his pathetically arrogant writing, wherein he pratically claims credit for CA, despite actually doing very little to even further the field. It's sad that people are beginning to think he really is a leader in the study. Please dissociate Wolfram and CA in your mind. Thanks...
    • No kidding. I've never before read a book in which every paragraph started with either "And" or "But." I think I'm including the opening paragraph here. If you're not laughing or shaking your head, you haven't read it.
      • I have read the book, and that is not the impression that I, nor many other people who've read it, came away with. On the contrary, he repeatedly refers to it as his discovery- "...the new kind of science I [emphasis mine] have developed...", "...my discovery...", "...one of the more important single discoveries in the whole history of theoretical science..."

        That's just in the first chapter, but it continues throughout. He makes little reference to others' work in the field, pretty much dismissing all work
  • by caramelcarrot (778148) on Wednesday December 15 2004, @05:00PM (#11097432)
    "...using cellular automata as a means of explaining higher order behavior (like Wolfram in A New Kind of Science)."

    Well, not quite sure if it can explain as high order behavior as Wolfram yet...
  • /. in the book (Score:5, Interesting)

    by JohnGrahamCumming (684871) * <slashdot@jPLANCKgc.org minus physicist> on Wednesday December 15 2004, @05:01PM (#11097445) Homepage Journal
    This is, indeed, an interesting book and the reviewer fails to point out that Emergence goes into detail concerning the karma, moderation and meta-moderation system of this here web site.

    Author seems to think taco is a genius or something, but it's still a good read :-) Towards the end where he's talking about emergent video games I got a little bored, but definitely a book that got me thinking. Worth reading even if you are aware of the way ants behave, because you probably don't know as much about slime mold as you should.

    John.
    • you probably don't know as much about slime mold as you should.

      Ooohhh yes I do matey, I played Baldurs Gate all the way through I'll have you know.

  • ugh (Score:2, Informative)

    I read the first two chapters or so of that book. It's totally an essay strrrreeeetched into a book. Terribly boring (in a lite-on-content sort of way). On the topic of taking recommendations from Slashdot: A poster raved about "The Non-Designers Design Book," so I bought it. It's not completely worthless for total amateurs (like me), but it's pretty much written for the purpose of teaching secretaries how to make better-looking newsletters. Lesson learned.
  • by wwest4 (183559) on Wednesday December 15 2004, @05:03PM (#11097462)
    ...but interesting, nonetheless. For two viewpoints that are more or less opposing, read Daniel Dennett and John Searle - the latter of whom is a latter-day dualist who talks a lot about emergence, aka emergent properties. Dennett thinks machines will be able to think, Searle doubts it.

    • Reminds me of an old quote about the study of AI,

      "The question of whether computers can think is like the question of whether submarines can swim." * "The question 'Can machines think?' is as ill-posed and uninteresting as the question 'Can submarines swim?'"
      - E W Dijkstra [possibility.com]

      Seems to me that emergent properties is what it's about. I've got to concede Dijkstra's point.

  • by Tackhead (54550) on Wednesday December 15 2004, @05:07PM (#11097495)
    > 2. Ignorance is useful. Ants communicate with a vocabulary of around 20 words/ideas.

    I knew our collective hive mind would come in handy someday:

    1. "I, for one, welcome our emergent overlords."
    2. "???"
    3. "Profit!"
    4. "In Soviet Russia, our groupthink comes from emergent behvaior, or is it the other way around?"
    5. "Who cares? Look, it's Natalie Portman!"
    6. "Does Netcraft confirm it?"
    7. "Yeah, but only in Korea."
    8. "Netcraft does not confirm it. Old people are not quite dead yet."
    9. "OK, that's the Monty Python reference out of the way. Has someone bashed China yet?"
    10. "No, and we also haven't bashed Micro$oft yet, at least not until this line.

    Crap. I'm only at #10 and the well's running dry. (What, you want me to yell "MEEPT!" or something?)

    If you're a glass-half-empty type: we won't be as useful in the underground sugar mines as I'd previously thought. We're only capable of half as many thoughts.

    If you're a glass-half-full type: or maybe we've achieved antlike emergent behavior using only ten words and ideas, making us twice as efficient as our formic emergent-behavior-exhibiting overlords!

  • by krahd (106540)
    If you're interested in emergent behaviour and like sci-fi thrillers, you must read Michael Crichton's Prey [crichton-official.com].

    I know a lot of people here seems to despise Crichton but, IMHO, he writes book that are really fun (and much better than the movies they span).. so I encourage everyone to give them a try.

    btw, if you like Prey you should read Andromeda Strain [crichton-official.com], also...

    --krahd

    mod me up, Scottie!
    • There is a good reason to despise Crichton: over the years he's degenerated from a moderately talented SF/thriller writer into a Luddite ideologue whose "novels" are thinly disguised political screeds -- and in the process, he's stopped doing his homework, which for a writer in his genre (especially one with his education) is unforgivable. His later novels, including Prey, have replaced storytelling with pseudoscientific hysteria.
      • Thank you.

        His basic theme doesn't change much: advanced technology and hubris gets us into trouble that only Mother Nature, in her serendipitous magnanimity, can rescue us from. Like Andromeda Strain ... the human race was on the verge of extinction from a space-born microbe (that wouldn't have bothered us if we hadn't been overstepping our bounds in the first place by building spacecraft) and we're saved at the last minute by a random mutation. Phooey. I've never really considered Crichton to be even
    • Pray? I don't get it. Sure, I'm not a fan of Crichton's books, but they're not that bad!
  • was about coming to term with Gentoo, guess not.
  • I use the following amusing/horrifying anecdote from Dawkins [amazon.com] in the Genetic Omnidominance Hypothesis [geocities.com] that sheds light on the real connection between ant colonies, brains and cities:

    ...scholars of revolutions may find the following passage from chapter 4, "Arms Races and Manipulation" particularly interesting:

    "Several species of ant have no workers of their own. The queens invade nests of other species, dispose of the host queen, and use the host workers to bring up their own reproductive young

  • by idontgno (624372) on Wednesday December 15 2004, @05:15PM (#11097578) Journal
    but isn't this terrain Douglas Hofstadter [indiana.edu] covered about twenty-five years ago in Gödel, Escher, Bach [wikipedia.org]? Does Johnson's book say much new? Has a quarter-century's "progress" in CA and AI brought us any closer to singularity [wikipedia.org]? And will I ever stop posting this comment in rhetorical question form?
    • but isn't this terrain Douglas Hofstadter covered about twenty-five years ago in Gödel, Escher, Bach?

      Exactly what I was thinking. I may have to read this book just for that comparison alone. For those who have not read it, I highly recommend it...it's not a weekend browser, but has some fascinating insight and thought experimentation. One of the most interesting books I've ever read. And the kind of books I usually like have more pictures than words :)
    • by Anonymous Coward
      Hofstadter's
      Contracrostipunctus
      Acrostically
      B ackwards
      Spells
      J.S.BACH
  • Try http://www.amazon.com/exec/obidos/tg/detail/-/067 1 872346/102-1898615-3811317?v=glance [amazon.com].
    It's a bit dated, since complexity theory and emergence are actually not all that new. People familiar with cellular automata modeling and games like SimCity will chuckle.

    But the book is fascinating, has great explanations of many of the concepts, and touches on many of the people who have made the study of complexity so fascinating. I'd definitely recommend it for a geek holiday gift.
  • This sound like the precursor science to Isaac Asimov's fictional Psychohistory [wikipedia.org].

    BTW has anybody else noticed the analogies between Asimov's original Foundation series and the adoption of Open Source/Free Licensed Software. We are about heading towards the second Stallman [stallman.org] crises : The Merchant Princes.

    "So by the same reasoning which make me sure that the Korellians will revolt in favor of prosperty, I am sure

    we will not revolt against it. The game will be played out to it's end.

    Trader Mallow from The Merch

  • Matrix (Score:3, Interesting)

    by Kallahar (227430) <kallahar@quickwired.com> on Wednesday December 15 2004, @05:28PM (#11097692) Homepage
    This was also a theme from the Matrix. The machine world was not controlled by a single overlord but was instead made up of billions of different programs. All the way down to the "wind" or the "bird" programs. Taken individually they're all rather simple and pointless, but when taken as a whole they build something much more valuable.
  • I quoted this excellent book and gave some future directions about using the bottom-up Emergence technique when dealing with Threat Modeling. Read the last chapter in my MSc paper Threat Modeling for Web Applications using the STRIDE model [securityworld.be] Comments welcome. Thanks
  • You know, as someone at an art school, I can't help but think "Gestalt Theory" when I read this summary.

  • by B747SP (179471) <slashdot@selfabusedelephant.com> on Wednesday December 15 2004, @05:40PM (#11097777)
    Emergence is a really interesting field to tinker in. I've been doing some work with this, have a couple of published papers on the application of agent based modelling to operations management problems.

    The essential concept is that each individual is a simple agent that operates autonomously, and makes very few very simple decisions as it goes about its work. The behaviour of one individual is unremarkable, but the behaviour that emerges from a large group of the same individuals is really quite amazing.

    Because the concepts are really quite logically simple, this stuff is really simple to program too. Just fire up perl or java or any language that has a similar capability to OO concepts, write a simple object - your agent - that behaves according to a simple set of rules and responds in defined ways to certain stimuli. Make a wrapper program to create the playing field, instantiate as many 'agents' as you see fit, and let them loose. Tweak, rinse, repeat.

    As an aside, when I was writing a simulation to emulate the behaviour of ants foraging (more to prove that perl and java were suitable languages for the task than to demonstrate anything new with ants per se), I went off and RTFM'ed quite a bit on ants. They're very interesting little critters in their own right. I picked the eyes out of the various behaviours of a bunch of different species of ants to come up with one that made a fun simulation (refer references below).

    The bare mechanical simplicity with which some of these critters operate is really quite amazing. Take, for example, the concept of trail laying. I guess it's pretty widely known that many species of ants lay trails from food sources back to the nest to guide other ants to the food. (Try: find a line of ants climbing up the wall in the kitchen or somewhere, moisten your finger, wipe straight through the line (washing off the trail). They'll be all disoriented for a little while, but they'll quickly re-establish the trail, largely by random search). Anyhoo, what's really quite cool is how one species does it. The trail is just an emission from the back end of the ant that wipes along the ground as it walks. The mechanics are such that if the ant has a full crop, it puts pressure on the digestive tract, and forces stuff out the back. If its only lightly fed, it only forces a bit out the back, if its had a big feed, it forces a lot out the back and lays a denser trail. The outcome is that the ants lay stronger trails to the better food sources. Elegant, isn't it!

    I could go on forever, but I won't. Some references below. Another behaviour that is probably even more interesting than trail laying is navigation. They're absolutely amazing. Various ants use various combinations of reference to the sun, counting the amount of ground that passes underneath them as they walk *AND* remembering turns!!!, and reference to major landmarks as they travel. Did I say amazing?

    Anyhoo, here's a bunch of references on ant behaviour if anyone's interesting.

    NOTE: slashdot doesn't like 'junk' characters, so I'm removing all the comment chars :-(
    #!/usr/local/bin/perl -w
    /*
    Dancing Ants. An agent-based simulation of ant scouting and
    foraging behaviour. Demonstrating the application of open-
    source programming tools to agent-based simulation.

    # B747SP, University of xxxxxxxxxxxx. 3rd December 2003

    # In this simulation, we define an 'ant' object with behavioural
    # patterns drawn from various published works on Biology, Zoology,
    # and Behavioural science. We define a 'foraging area', then release
    # those ants into it. And then we observe...

    # What we know about ants...

    Note: These 'definitions' merely describe the behaviour of a fictional, theoretical
    ant specifically 'bred' in the mind of the author for this specific simulation.
    Their behaviours are derived from the various species of ants studied in the
    belowreferenced research papers. The behaviour describe

    • > I picked the eyes out of [...] ants
      > ... a fun ...

      Um...
      Get out more...
      Please...

    • Make a wrapper program to create the playing field, instantiate as many 'agents' as you see fit, and let them loose. Tweak, rinse, repeat.

      Better yet, use a simulation environment like breve [spiderland.org] and you get 3d rendering, collision detection, basic physics, and a lot more for free.
      • Better yet, use a simulation environment like breve and you get 3d rendering, collision detection, basic physics, and a lot more for free.

        We did look at a bunch of those tools. An argument that I was trying to make, and trying to demonstrate, was that many common-or-garden programming languages - perl, java et al - are perfectly suitable tools for this type of work. There are a lot of simulation environments around, and they all have their quirks, their own languages, and stuff. What I wanted to demonstra

    • observations
      Theres some interesting observational research, Oscillations and Chaos in Ant Societies, R.V. Sole, O. Miramontes, and B.C. Goodwin, J. Theor. Biol. 161, pp.343-357, 1993.

      In David Suzuki's, The Sacred Balance [sacredbalance.com], Brian Goodwin (author also of, HOW THE LEOPARD CHANGED ITS SPOTS [amazon.com]) made some interesting observational discoveries with ants. Synchronous emergent behaviour arose when individual *chaotic* ants reached a certain density. Goodwin concluded that ...

      • ... living near the edge of chaos give
  • 2. Ignorance is useful.

    If that were true, my company would be the most productive on the planet.

    Is Christmas vacation here yet? :-\

  • Interesting ideas (Score:2, Insightful)

    by xnot (824277)
    Kind of like the continuum going from observing at the atomic level to observing at the macroscopic level. The physics of the atomic level is VERY different then the physics of the macroscopic level. Understandably, when you get to a point where you can't use one model over the other, things can get pretty hairy.

    Can you say that the atomic level CAUSES the macroscopic level, i.e. one level emerges out of the other? My feeling is, it doesn't make much of a difference. The interactions you get depend upon yo
  • After Thought (Score:2, Informative)

    by bgalbraith (741719)
    Another good book on the subject of emergent systems is After Thought [amazon.com] by James Baily. It is a quick and enjoyable read that takes a look at the evolution of mathematical and philosophical attempts at describing our universe from the ancient Greeks to modern day scientists. Specifically, he focuses on how we attempt to model the human brain electronically, and touches on parallel computing, cellular automata, genetic algorithms, and the techniques required to allow a machine to learn.
  • It's worth mentioning here that, unlike some of the other books mentioned, 'Emergence' ends up tying the concepts to modern applications. For example, it discusses Amazon.com's use of self-organizing groups.
  • by Zukix (641813) on Wednesday December 15 2004, @06:34PM (#11098280)
    I found the following to be surprising and useful background for the glut of writing about complexity/emergence/universality etc. Lots of historical detail from J. S. Mill onwards about the use of emergence in philosophy. Good bibliography too of which I can recommend the Kaufman books as good fun:
    http://plato.stanford.edu/entries/properties-emerg ent/ [stanford.edu]
  • I'm surprised about the statement regarding economists supporting centralized planning of economies. Good economists understand that the free market is an emergent system, and planned centralized economies have a long history of failure.

    Of course a lot of socialist economists get the press, because there are so many liberal leftists in academia.

    Why people who believe in evolution and not in creationism yet don't believe in the emergent free market but instead believe in central socialist planning is beyo
  • It would be really interesting to try to study and correlate some apparently phenomona in animal behavior and sociology.

    For example, swarming of locusts is one such phenomenon. It does not happen every year. It does not happen everywhere. Yet, when it happens it takes the shape of enormous disasters, such as what has been happening in Africa, the Middle East and Australia. Even Cyprus and the Canary Islands are affected!

    Also, look at how some teens hanging out or at a bar would be under peer pressure an

    • Re:Prey (Score:5, Interesting)

      by Rei (128717) on Wednesday December 15 2004, @05:00PM (#11097431) Homepage
      The thing is, there's no reason to be scared of autonomous organization - it is literally everywhere around us.

      Swarming/flocking/schooling algorithms are a great example of this. All it takes is a desire to be close to your neighbors but not too close, and the swarm/flock/school functions largely on its own - it can even go around obstacles and re-merge, it optimizes into aerodynamic shapes, etc.

      I love complexity from simplicity. One of my favorites occurs from the standard predator/prey population equation. If you run it for a while, it switches into repeating cycles of population size. However, the positions and numbers of cycles are dependant on the equation conditions. If you plot the cycles vs. the starting conditions, you get this beautiful graph of the data starting at a single point, then branching, and again, faster and faster until it forms into pure chaos... and then from the chaos, emerges three clean branches, which then fall to chaos again.
      • The thing though, even when technology *isn't* evil in Crichton's books (as in Congo) the books are still about how some discovery could change the world but doesn't (semi-intelligent apes, cloned dinosaurs, time travel, etc) -- in the end *always* the discovery gets lost and the world is no different than before. Wouldn't it be more interesting to read about how time travel or cloned dinosaurs would change society?
    • No, no it's not. Now go find a sci-fi thread somewhere.
    • It's there, it allows birds/ants to communicate in a method that we can't detect. Is that possible?

      Possible? Everything is. But who needs it when the things we can detect seem to run the gamut? See the original formulation of Occam's Razor.
    • But the world changed while he was writing Out of Control largely due to the exaggerated importance placed on Mitchell, Hraber and Crutchfield's 1993 paper [santafe.edu] which cast aspersions on Langton's lambda and implicitly on the whole notion of "border of order--edge of chaos".

      Wolfram's reunification of his own old Class 3 and Class 4 under his more recent Principle of Computational Equivalence goes even further in a direction I'd rather see us retreat [meme.com.au] from.

      I actually read the book by Johnson reviewed here for con